With the growth of information communication technology, various wireless communication technologies are under development. Among the wireless communication technologies, wireless local area network (WLAN) technology enables wireless Internet access at home or in offices or specific service provision areas using a mobile terminal such as a personal digital assistant (PDA), laptop computer, portable multimedia player (PMP) or the like on the basis of radio frequency technology.
To overcome the limitations of communication rate, which have been cited as a weak point of WLAN, recent technical standards have introduced systems with increased network rate and reliability and extended wireless network coverage. For example, IEEE 802.11n supports high throughput (HT) of a data rate of 540 Mbps or higher and introduces MIMO (Multiple Input Multiple Output) technology which uses multiple antennas for both a transmitter and a receiver in order to minimize a transmission error and optimize a data rate.
M2M (Machine-to-Machine) communication technology is under discussion as a next-generation communication technology. In IEEE 802.11 WLAN system, IEEE 802.11ah is developed as a technical standard for supporting M2M communication. For M2M communication, a scenario in which a small amount of data is transmitted/received at a low speed occasionally in an environment having a considerably large number of devices can be considered.
Communication in a WLAN system is performed through a medium shared by all devices. When the number of devices increases as in M2M communication, it is necessary to improve a channel access mechanism more efficiently in order to reduce unnecessary power consumption and generation of interference.